The invention relates to breathing protection equipment including a breathing mask provided with a regulator having a plurality of operating modes, selectable by means that are not in the field of view of the user while using the mask.
A major, but non-exclusive, use of such a mask lies in aviation equipment; it is conventional to have three operating modes: "normal" mode supplying the user with a mixture of ambient air and oxygen; "100%" mode supplying pure oxygen; and "emergency" mode supplying pure oxygen under pressure.
As a general rule, the operating mode is selected by actuation of one or more mechanical switches placed on the regulator body of the mask at a location that is outside the field of view of the user. In other cases, the operating mode is selected automatically in response to information supplied by a sensor integrated in the regulator and serving, for example, to detect depressurization of the cabin.
In both cases, the user cannot visually check the operating mode of a mask while it is being worn: the user must feel the position of the switch or remove the mask to look at its position. In practice, such verification is generally not performed. Consequently there is a risk of leaving the regulator in a mode that is not appropriate, e.g. "100%" or "emergency" mode when that is unnecessary (thereby using up the oxygen supply pointlessly) or in the "normal" mode when there is smoke in the cabin (a situation that could lead to the user being physically harmed).